Week 3.2: The neurobiological aspects of the stress response Flashcards
This is the body’s automatic reaction to perceived threats, preparing us to either confront (fight) or escape (flight) the danger.
Fight or Flight Response
Some experts add this as a third reaction, where an individual becomes immobile in the face of a threat
Freeze
The body’s attempt to maintain a stable internal environment.
When homeostasis is threatened, the body initiates responses to restore balance. This includes changes in heart rate, hormone levels, and behavior.
Homeostasis
What are causes of stress?
Threats to Well-being: Stress can arise from situations that threaten an individual’s physical or psychological well-being.
Perceived Threats: Even if a situation isn’t objectively dangerous, if it’s perceived as threatening, it can cause stress.
An Austrian-Canadian endocrinologist known for his pioneering work on stress. He was nominated for the Nobel Prize multiple times for his contributions to endocrinology and the study of stress.
Hans Selye
Selye’s term for the body’s general response to stress
General Adaptation Syndrome (GAS)
The body’s response to demands placed upon it, involving the production of stress hormones.
General Adaptation Syndrome / Stress Response
What are the Stages of GAS (General Adaptation Syndrome)?
Alarm Stage
Resistance Stage
Exhaustion Stage
The initial reaction to a stressor, activating the fight or flight response.
Alarm Stage
The body attempts to adapt to the stressor.
Resistance Change
Prolonged exposure to the stressor depletes the body’s resources, leading to potential health problems.
Exhaustion Stage
The main stress hormone in humans, produced in the adrenal cortex and released into the bloodstream.
Cortisol
As these hormones regulate glucose metabolism, so ‘gluco’, they are synthesised in the adrenal cortex, so ‘cort’, and chemically the structure is classified as steroid, so ‘oid’, which is the last part of the word.
Glucocorticoids
Has a low affinity for cortisol and is primarily activated by high cortisol levels during stress.
Glucocorticoid Receptor (GR)
Has a high affinity for cortisol and is activated by low or basal cortisol levels.
Mineralocorticoid Receptor (MR
The fluid inside the cell
Cytoplasm
The cell’s control center
Nucleus
Once GR is in the nucleus, it attaches to these specific parts of the DNA
Glucocorticoid Response Elements (GREs
Are special proteins found on the surface of or inside cells.
They act like locks that can be opened by specific keys, which are usually molecules like hormones, neurotransmitters, or drugs.
Receptors
What are the physiological roles of cortisol?
1) Controls energy metabolism
2) Maintains electrolyte balance and blood pressure
3) Modulates immune responses
Suppresses the immune system to prioritize immediate survival needs.
Cortisol
The endocrine system includes hormones, glands, and receptors.
Hormones like cortisol are part of this system, which uses chemical signals to regulate various body functions.
Endocrine System
How is cortisol produced and regulated?
1) Stress Trigger:
Hypothalamus releases two hormones: CRH and AVP
2) Hormone Cascade:
CRH and AVP tell the pituitary gland to release ACTH.
ACTH travels to the adrenal glands (on top of the kidneys).
The adrenal glands produce and release cortisol.
3) Cortisol’s Role:
Energy Release: Cortisol helps release stored glucose from the liver for energy to face the stressor.
Immune Suppression: Cortisol temporarily suppresses the immune system to focus on immediate survival.
4) Negative Feedback Regulation: When cortisol levels are high, it signals the brain to reduce its production.
This reduces the release of ACTH and CRH, lowering cortisol levels and maintaining balance.
Neurotransmitters are part of this system, which uses electrical and chemical signals to communicate between nerve cells.
Nervous System
